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+/*
+
+ rdev.c - query/set root device.
+
+-------------------------------------------------------------------------
+
+Date: Sun, 27 Dec 1992 15:55:31 +0000
+Subject: Re: rdev
+From: almesber@nessie.cs.id.ethz.ch (Werner Almesberger)
+To: Rik Faith <faith@cs.unc.edu>
+
+There are quite a few versions of rdev:
+
+ - the original rootdev that only printed the current root device, by
+ Linus.
+ - rdev that does what rootdev did and that also allows you to change
+ the root (and swap) device, by me.
+ - rdev got renamed to setroot and I think even to rootdev on various
+ distributions.
+ - Peter MacDonald added video mode and RAM disk setting and included
+ this version on SLS, called rdev again. I've attached his rdev.c to
+ this mail.
+
+-------------------------------------------------------------------------
+
+Date: 11 Mar 92 21:37:37 GMT
+Subject: rdev - query/set root device
+From: almesber@nessie.cs.id.ethz.ch (Werner Almesberger)
+Organization: Swiss Federal Institute of Technology (ETH), Zurich, CH
+
+With all that socket, X11, disk driver and FS hacking going on, apparently
+nobody has found time to address one of the minor nuisances of life: set-
+ting the root FS device is still somewhat cumbersome. I've written a little
+utility which can read and set the root device in boot images:
+
+rdev accepts an optional offset argument, just in case the address should
+ever move from 508. If called without arguments, rdev outputs an mtab line
+for the current root FS, just like /etc/rootdev does.
+
+ramsize sets the size of the ramdisk. If size is zero, no ramdisk is used.
+
+vidmode sets the default video mode at bootup time. -1 uses default video
+mode, -2 uses menu.
+
+-------------------------------------------------------------------------
+
+Sun Dec 27 10:42:16 1992: Minor usage changes, faith@cs.unc.edu.
+Tue Mar 30 09:31:52 1993: rdev -Rn to set root readonly flag, sct@dcs.ed.ac.uk
+Wed Jun 22 21:12:29 1994: Applied patches from Dave
+ (gentzel@nova.enet.dec.com) to prevent dereferencing
+ the NULL pointer, faith@cs.unc.edu
+
+-------------------------------------------------------------------------
+
+*/
+
+/* rdev.c - query/set root device. */
+
+usage()
+{
+
+ puts("usage: rdev [ -rsv ] [ -o OFFSET ] [ IMAGE [ VALUE [ OFFSET ] ] ]");
+ puts(" rdev /dev/fd0 (or rdev /linux, etc.) displays the current ROOT device");
+ puts(" rdev /dev/fd0 /dev/hda2 sets ROOT to /dev/hda2");
+ puts(" rdev -R /dev/fd0 1 set the ROOTFLAGS (readonly status)");
+ puts(" rdev -s /dev/fd0 /dev/hda2 set the SWAP device");
+ puts(" rdev -r /dev/fd0 627 set the RAMDISK size");
+ puts(" rdev -v /dev/fd0 1 set the bootup VIDEOMODE");
+ puts(" rdev -o N ... use the byte offset N");
+ puts(" rootflags ... same as rdev -R");
+ puts(" swapdev ... same as rdev -s");
+ puts(" ramsize ... same as rdev -r");
+ puts(" vidmode ... same as rdev -v");
+ puts("Note: video modes are: -3=Ask, -2=Extended, -1=NormalVga, 1=key1, 2=key2,...");
+ puts(" use -R 1 to mount root readonly, -R 0 for read/write.");
+ exit(-1);
+}
+
+#include <stdio.h>
+#include <string.h>
+#include <ctype.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <dirent.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+
+#define DEFAULT_OFFSET 508
+
+
+static void die(char *msg)
+{
+ perror(msg);
+ exit(1);
+}
+
+
+static char *find_dev(int number)
+{
+ DIR *dp;
+ struct dirent *dir;
+ static char name[PATH_MAX+1];
+ struct stat s;
+
+ if (!number) return "Boot device";
+ if ((dp = opendir("/dev")) == NULL) die("opendir /dev");
+ strcpy(name,"/dev/");
+ while (dir = readdir(dp)) {
+ strcpy(name+5,dir->d_name);
+ if (stat(name,&s) < 0) die(name);
+ if ((s.st_mode & S_IFMT) == S_IFBLK && s.st_rdev == number) return name;
+ }
+ sprintf(name,"0x%04x",number);
+ return name;
+}
+
+/* enum { RDEV, SDEV, RAMSIZE, VIDMODE }; */
+enum { RDEV, VIDMODE, RAMSIZE, SDEV, __syssize__, ROOTFLAGS };
+char *cmdnames[6] = { "rdev", "vidmode", "ramsize", "swapdev",
+ "", "rootflags"};
+char *desc[6] = { "Root device", "Video mode", "Ramsize", "Swap device",
+ "", "Root flags"};
+#define shift(n) argv+=n,argc-=n
+
+int main(int argc,char **argv)
+{
+ int image,offset,dev_nr, i, newoffset=-1;
+ char *device, cmd = 0, *ptr, tmp[40];
+ struct stat s;
+
+ device = NULL;
+ if (ptr = strrchr(argv[0],'/'))
+ ptr++;
+ else
+ ptr = argv[0];
+ for (i=0; i<=5; i++)
+ if (!strcmp(ptr,cmdnames[i]))
+ break;
+ cmd = i;
+ if (cmd>5)
+ cmd=RDEV;
+ offset = DEFAULT_OFFSET-cmd*2;
+
+ while (argc > 1)
+ {
+ if (argv[1][0] != '-')
+ break;
+ else
+ switch (argv[1][1])
+ {
+ case 'R':
+ cmd=ROOTFLAGS;
+ offset = DEFAULT_OFFSET-cmd*2;
+ shift(1);
+ break;
+ case 'r':
+ cmd=RAMSIZE;
+ offset = DEFAULT_OFFSET-cmd*2;
+ shift(1);
+ break;
+ case 'v':
+ cmd=VIDMODE;
+ offset = DEFAULT_OFFSET-cmd*2;
+ shift(1);
+ break;
+ case 's':
+ cmd=SDEV;
+ offset = DEFAULT_OFFSET-cmd*2;
+ shift(1);
+ break;
+ case 'o':
+ if (argv[1][2])
+ {
+ newoffset=atoi(argv[1]+2);
+ shift(1);
+ break;
+ } else if (argc > 2) {
+ newoffset=atoi(argv[2]);
+ shift(2);
+ break;
+ }
+ /* Fall through. . . */
+ default:
+ usage();
+ }
+ }
+ if (newoffset >= 0)
+ offset = newoffset;
+
+ if ((cmd==RDEV) && (argc == 1 || argc > 4)) {
+ if (stat("/",&s) < 0) die("/");
+ printf("%s /\n",find_dev(s.st_dev));
+ exit(0);
+ } else if ((cmd != RDEV) && (argc == 1 || argc > 4)) usage();
+
+ if ((cmd==RDEV) || (cmd==SDEV))
+ {
+ if (argc == 4) {
+ device = argv[2];
+ offset = atoi(argv[3]);
+ }
+ else {
+ if (argc == 3) {
+ if (isdigit(*argv[2])) offset = atoi(argv[2]);
+ else device = argv[2];
+ }
+ }
+ }
+ else
+ {
+ if (argc>=3)
+ device = argv[2];
+ if (argc==4)
+ offset = atoi(argv[3]);
+ }
+ if (device) {
+ if ((cmd==SDEV) || (cmd==RDEV))
+ { if (stat(device,&s) < 0) die(device);
+ } else
+ s.st_rdev=atoi(device);
+ if ((image = open(argv[1],O_WRONLY)) < 0) die(argv[1]);
+ if (lseek(image,offset,0) < 0) die("lseek");
+ if (write(image,(char *)&s.st_rdev,2) != 2) die(argv[1]);
+ if (close(image) < 0) die("close");
+ }
+ else {
+ if ((image = open(argv[1],O_RDONLY)) < 0) die(argv[1]);
+ if (lseek(image,offset,0) < 0) die("lseek");
+ dev_nr = 0;
+ if (read(image,(char *)&dev_nr,2) != 2) die(argv[1]);
+ if (close(image) < 0) die("close");
+ printf(desc[cmd]);
+ if ((cmd==SDEV) || (cmd==RDEV))
+ printf(" %s\n", find_dev(dev_nr));
+ else
+ printf(" %d\n", dev_nr);
+ }
+ return 0;
+}
+
+
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